I have 2 cats, both 15 and both have hyperthyroidism. One is doing fine on meds and also has mild dementia (peeing inside, odd behaviour) but is essentially happy. The other isn't doing well at all. She is pulling out fur, and it's been confirmed that her thyroid levels are fine, as are her kidneys, so that's not the reason. She had to be at the vets for over an hour whilst they had 4 vets trying to get bloods from her a couple of weeks ago. We took her back yesterday to see if a steroid injection would help, in case the fur pulling is itchiness, and she was completely terrified - shaking. No improvement yet and I'm wondering if this is time to consider putting to sleep. She's purring rarely, very skinny, not cleaning herself well and just seems miserable. I don't want to put her through another barrage of tests and the vets did a very thorough blood panel 2 weeks ago - they're not clear on what it could be, so it would be a fishing expedition.
I don't want to feel like we're giving up on her when we don't actually know what is wrong, but I also can't stand to see her so unhappy. How do you know when it's time?